Antistatic photographic film



w. s. RICHARDSON 2,649,374

, ANTISTATIC PHOTOGRAPHIC FILM Aug. 18, 1953 Filed June 10, 1949 EMULSION CON774/N/N6 C'ONDENJAT/DN PRODUCT 0F FORMALDEHYDE AND NAPHTHALENE SULFON/C ACID EMULSION SUPPORT "INTI- $7AT/C LAYER 0F CONDENSATION PRODUCT 0F FORM/ILDEHYDE AND NAPHTHALENE SULFON/C ACID APPLIED FROM WATER SOLUTION EMULSION .suPPok'r ANTI- STAT/C LAYER 0F CONDENSAT/ON PRODUCT 0F FORMALDE HYDE AND N/IPHTHALENE .SULFON/C ACID /N COLLOID/IL CARRIER WINFIELD s. RICHARDSON.

' INVENTOR ATTORNEYS Patented Aug. 18, 1953 AN TISTATIC PHOTOGRAPHIC FILM Winfield S. Richardson, Rochester, N. Y., assignor to Eastman Kodak Company, Rochester, N. Y., a. corporation of New Jersey Application 1...... 10, 1949, Serial No. 98,382

I 4 Claims. (01. 95-9) This invention relates to photographic film and particularly to a. film protected against static.

The accumulation of electrical charges on photographic film has been the cause of considerable trouble. These charges are produced by the friction of the film moving over rollers or past the gates of a camera and when discharged are manifested as irregular fogged patterns in the emulsion of the film after it'has been developed. These static effects are particularly noticeable in a film provided with a cellulose nitrate support, although with the advent of high speed emulsions practically any film support will become sufficiently electrified during manufacture or use so that the discharges of stored-up static electricity will affect the sensitive layer. Static markings on film are thought to result also upon separation of emulsion from base during unwinding of a, stock roll when the roll was wound at a humidity suificiently high to impart sticking.

Attempts have been made to overcome static in photographic films by the application of various layers to the film support. These layers have, in general, consisted of materials designed to dissipate the electric charges by providing the film with a conducting surface. Materials which absorb moisture and, therefore, provide a conducting surface have frequently been employed. Most of these methods have not proven entirely satisfactory with the-newer high speed emulsions.

It is therefore an object of the present invention to provide a novel and efi'ective-means of protecting a sensitive photographic film against static. A further object is to'provide a method of coating photographic film to reduce its static tendency. Other objects will appear from the following description of my invention.

These objects are accomplished by incorporating in one of the layers of a photographic film or as a separate layer on the film; an alkali metal or ammonium salt of a, condensation product of formaldehyde anda naphthalene sulfonic acid.

The accompanying drawing" 'showsj sectional views of film constructed 'according'to'my "invention.

The anti-static agents which I propose to use are condensation products of an aldehyde such as formaldehyde with naphthalene sulfonic acids (Ullmann, Enzyklopadie der technischen Chemie, 2nd Auflage (1930) 5 Band, page 686 and H. Wagner, Chemiker Zeitung, vol. 46 (1922), page 801). These products are sold under the trade name Tamol and I have used the specific products designated Tamol NNO and Tamol P. These are relatively neutral amorphous solid products having no odor, are quite soluble in water and are compatible with organic solvents in a narrow range. When dissolved in water at low concentrations they give essentially clear colorless solutions without odor which do not decompose with standing. More concentrated solutions have a slight yellowish color. Their solubility characteristics require initial dispersion in water before other organic solvents can be added. The Tamols are alkali metal salts such as the sodium salts, or the ammonium salts.

When used to prevent static on sensitive photographic film, the Tamols may be included in the sensitive emulsion layer, in an overcoating layer or in a backing layer. They may be applied from water solution or coated as a separate layer, in which case they are included in a carrier such as cellulose nitrate, oxidized cellulose acetate, ethyl cellulose phthalate, cellulose acetate phthalate, carboxy methyl cellulose, polyvinyl alcohol polyglycol dilaurate, cellulose acetate sulfate and high molecular weight polyethylene glycols such as Carbowax 6000.

My anti-static agents possess such physical properties that when applied from aqueous solution to the back of a cellulose ester film, they form a clear, transparent layer on the film without any undesirable physical or photographic effects. They are, therefore, preferably applied in this way.

The following examples illustrate methods of applying the anti-static agent according to my invention.

Example 1 Twenty grams of the sodium salt of a condensation product of formaldehyde and naphthalene sulfonic acid were ground to a very fine powder and added slowly to 200 grams of regular motionpicture positive emulsion with constant stirring for five minutes. The emulsion was then agitated Example 2 film was experienced, and in such cases, the ad-' dition of .2 grams of Triton N-100 (alkylated aryl polyether alcohol) to the solution was found to improve the wetting characteristics and facilitate coating. The following electrical results were obtained:

Backing resistivity ohms 50% R. H. Check 100,000 Treated sample 1.3 Example 3 Nine grams of the sodium salt of a condensation product of formaldehyde and naphthalene sulfonic acid was dissolved in '70 grams of distilled water and added to a solution of 2.1 grams of cellulose acetate phthalate and 2 grams of triethanolamine dissolved in 600 grams of methyl alcohol. A sample of motion-picture negative film after treatment with solution thus prepared showed the following electrical properties:

Backing resistivity ohms 10 50% R. H. Untreated check 100,000 Treated sample 11'! Resistivity (ohms)=ohms (measured) Spacing between contact electrodes Length of electrodes In the accompanying drawing:

Fig. 1 is a sectional view of one modification of photographic film constructed according to my invention. As shown therein, a film support 40 of cellulose ester has coated thereon a layer H of gelatino silver halide emulsion containing a condensation product of formaldehyde and naphthalene sulfonic acid. Another modification of my invention is illustrated in Fig. 2 which shows a sectional view of a film having the support 10 coated on one side with a sensitive emulsion layer l2 and on the opposite with an anti-static layer 13 of a condensation product of formaldehyde and naphthalene sulfonic acid, coated from water solution.

Fig. 3 shows a film similar to that of Fig. 2, in which the anti-static layer I4 is coated from a solution of a condensation product of formaldehyde and naphthalene sulfonic acid in a colloidal carrier such as cellulose acetate phthalate triethanolamine salt.

It will be understood that my invention is capahle of numerous modifications within the scope of the appended claims.

I claim:

1. .An enti static photographic film comprising a cellulose ester support having thereon a silver halide emulsion layer and in one of the layers of said film an alkali metal salt of the condensation product of formaldehyde and naphthalene sulfonic acid.

2. An anti-static photographic film comprising a cellulose ester support having on one side thereof a silver halide emulsion layer and on the opposite side thereof a layer of an organic acid ester of cellulose containing an alkali metal salt of the condensation product of formaldehyde and naphthalene sulfonic acid.

3. An anti-static photographic film comprising a cellulose ester support having on one side there'- of a silver halide emulsion layer and on the opposite side thereof a layer of an alkali metal salt of the condensation product of formaldehyde and naphthalene sulfonic acid.

4. An anti-static photographic film comprising a cellulose ester support having on one side thereof a silver halide emulsion layer and on the opposite side thereof a layer of an alkali metal salt of the condensation product of formaldehyde and naphthalene sulfonic acid coated from a solution of approximately 5 grams of said salt per 1000 grams of water.

WINFIEID S. RICHARDSON.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,972,208 Tucker Sept. 4, 1934 2,118,059 Slack et a1 May 24, 1938 2,139,778 Slack et al. Dec. 13, 1938 2,186,734: Schneider Jan. 9, 1940 2,420,610 Mueller May 13, 1947 2,527,262 Hart et al. Oct. 24, 1950 FOREIGN PATENTS Number Country Date 610,941 Great Britain Oct. 22, 1948 OTHER REFERENCES Schwartz et a1., Surface Active Agents, published March 11, 1949, Interscience Publishers, Inc, pages 119 and 120 cited. 7 

1. AN ANTI-STATIC PHOTOGRAPHIC FILM COMPRISING A CELLULOSE ESTER SUPPORT HAVING THEREON A SILVER HALIDE EMULSION LAYER AND IN ONE OF THE LAYERS OF SAID FILM AN ALKALI METAL SALT OF THE CONDENSATION 